biomassandbioenergy35(2011)2608e2618

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Generationofbioenergyandbiofertilizeronasustainableruralproperty

SoniaValleWalterBorgesdeOliveira1,AlexandreBevilacquaLeoneti*,GlaucoMateusMagriniCaldo,MarcioMattosBorgesdeOliveiraDepartmentofAdministrationeFEA-RPeUniversityofSaoPaulo(USP)-Av.Bandeirantes3900,MonteAlegre,14040-905,RibeiraoPreto,SP,Brazil

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Articlehistory:Received4February2010Receivedinrevisedform21February2011Accepted22February2011Availableonline3April2011

Keywords:SustainabilityBiodigesterBiodieselBiofertilizerBiogas

1.Introduction

abstract

Energysourceshavebecomeafocusoflegal,ethical,socialandeconomicpressuresduetoincreasingenvironmentalproblems.Nonrenewableenergysourcesarebeingincreasinglyreplacedbyothersourcesthatarerenewableandlesspollutive,withtechnologiesaimedatsustainability.Companiesthatadoptalternativeformsofenergywillbeabletoincreasetheircompetitivenessandusewastestogenerateenergy,whichisanecologicalandeconomicalefciencyapproach.IntheinteriorofthestateofSaoPaulo,Brazil,aruralproducerofporkcracklingandcoffeeevaluatedtheentireproductioncycleofhisproductsandwastes,seekingtoachieveenergyselfsufciencyandidentifynewpossibilitiesforgainsthroughcostreductions.Biodiesel,soapanddetergentareproducedwiththewasteanimalfatleftfromtheproductionofporkcrackling.Pigfarmwastesbecomebiomassforabiodigester,whichproducessufcientbiogastokeepthepigletswarm,drythecoffee,frytheporkcrackling,andgenerateelectricity,amongotheruses.Thebiofertilizerproducedbythebiodigesterhelpsfertilizecoffeeandcornplantations.Thepurposeofthisarticleistodemonstratetheecologicalandeconomicfeasibilityoftheproject.Theresearchmethodusedhereisacasestudyinvolvingqualitativeanalysesofenvironmentalandsocialvariablesandquantitativeanalysesofeconomicvariables.Itisconcludedthattheinvestmentmadeinthisprojectyieldsexcellentreturns,withsavingsof100%infuels,50%inelectricenergyand40%infertilizer,inadditiontogainsfromtheproductsdevelopedwiththewastes.2011ElsevierLtd.Allrightsreserved.

andbytheriskofclimatechangescausebytheintensiveuseofenergysourcesthatgenerategreenhousegas(GHG)emissions.

Theenergycrisisandtheenvironmentalproblemsresultingfromtheuseofpollutiveandnonrenewablesourcesofenergyhavechangedtheworldwidescenarioonthistheme,leadingtothesearchforsustainablesolutionsinthethreeambits:economic,environmentalandsocial.Theseaspectscanbetranslatedbythevolatilityoftheworldsfossilfuelmarkets

Newmodelsofenergyproductionandconsumptionmustbedevelopedusingrenewablesourcesofenergysuchaswind,solar,biomass,andoceanenergyproducedbywaves,currentsandtides.Theadoptionofgreenandsustainabletechnologiesinthelifestyleofsocietiesisanimportantsolutiontotheproblemofenergy[1].However,oneofthegreatestchallenges

*Correspondingauthor.Tel.:551636024751(USP).E-mailaddresses:soniavw@terra.com.br(S.V.WalterBorgesdeOliveira),ableoneti@usp.br(A.B.Leoneti),mmattos@usp.br(M.M.BorgesdeOliveira).

1

Tel.:551636024751(USP)

0961-9534/$eseefrontmatter2011ElsevierLtd.Allrightsreserved.doi:10.1016/j.biombioe.2011.02.048

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ofthistaskistheintroductionofmajorchangesinenviron-mentsadaptedtotraditionalformsofenergy,notonlyfromthetechnologicalstandpointbutalsofromthehumanaspectofadaptationtoandcomfortablenesswithexistinginstalla-tions,whichmaybethemoredifcultaspecttoovercome.Anypossiblealternativesforthesolutionofenvironmentalproblemswillbestronglyweightedbytheeconomicfactor.AccordingtoNagelandMeyer[2],ecologicalsolutionsusuallyleadtoeconomysavingsbecausereducingtheconsumptionofrawmaterialsandenergy,recyclingorreusingproductsarebothecologicallyandeconomicallysound.Hence,ecologicalandeconomicefciencymustbeachieved.Althoughbiomasshasahighenergypotential,theprac-ticesofitsexploitationrequirecomprehensivemanagement,sincethesepracticesmaybeveryharmfultotheenviron-ment,notonlyintermsofundesirableemissionsbutalsoduetotheenvironmentaldegradationresultingfromunbalancedexploitation.TheguidelinesoftheKyotoProtocolencouragetheuseofrenewableandlesspollutiveenergysourcesindevelopingcountries.ThegoalproposedattheUnitedNationsClimateChangeConferenceheldin1997inKyoto,Japan,isanaveragereductionof5.2%inGHGemissionsbetween2008and2012.Thegoalreferstothelevelofgasesemittedintotheatmo-spherein1990.Thisreductionisencouragedbythepossibilityfordevelopingcountriestonegotiatetheirreductions,ach-ievedbyCleanDevelopmentMechanisms(CDM),withdevel-opedcountriesthroughthesaleofcarboncredits.InBrazil,theuseofbiomassasanenergysourceisincreasingyearafteryear,seekingtoencouragethevaluationofenvironmentalandeconomicaspects.Thus,alcohol,bio-diesel,biogas,sugarcanebagasse-poweredthermoelectricplants,andothers,havebeengaininggroundintheBrazilianscenario,replacingtraditionalfossilfuels.Inthe1970sand80stherewasastrongincentivefortheinstallationofruralbiodigestersinnortheasternBrazil,althoughtheprogramsubsequentlylostmomentum.Withthepossibilityofcarboncreditsales,thisenergymodalityregaineditsformerposition,asdidothermethanegeneratingprocesses.Biodiesel,anotherrenewablesourceofenergy,hasbecomeafocusofattentioninrecentyears,mainlyduetoitschar-acteristicsofreducedpollutionanditsreasonablysimpleproductiontechnique.Theuseofbiodieselreducestheemissionsofcarbonmonoxide(CO),particulatematerial(PM),sulfuroxide(SOx),totalhydrocarbons(HC),andalargepartofthetoxichydrocarbonswithcarcinogenicpotential.Fromtheeconomicstandpoint,biodieselcanbeproducedfromseveraltypesofoilsandfats,bothvegetableandanimal,includingwastefats.Concomitantlytotheuseofalternativeenergysources,wastesandby-productsofproductionprocesseshavealsogainedground,demonstratingtheimportanceofcostreduc-tionswithaviewtosustainabledevelopment.

2.Objectives

Thispaperaimstodemonstratetheecologicalandeconomicfeasibilityofaruralenterpriseforpigbreedingand

processing,andcoffeeandcornproduction,basedontheconceptsofsustainability.Thespecicobjectivesweretoevaluatethepossibilityofusingthewastesgeneratedontheproperty;evaluatethepossibleenergysourcescompatiblewiththeenterprise;andanalyzetheitsenvironmentalandsocialvariables.

3.Theoreticalreferences

Energyisoneofthemostimportantresourcesfortheeconomicdevelopmentofacountry[3].Energysourcescanbedividedintotwogroups:biomass(alsocalledtraditional)andnon-biomass(alsocalledcommercial)[4].Biomass,whichiscomposedoforganicmatterproducedbybiologicalprocessesinvolvingthecaptureofsolarenergy,hasahighenergypotentialwhichisalsorenewable.Thevariousformsofbiomassincludewood,plants,foodrests,animalexcrements,domesticsewage,industrialwastewaters,andseveralotherelementsorresiduesoforganiccomposition.Uponundergoingconversionprocessessuchasburning,digestionbymicroorganisms,fermentation,chemicalreaction,andothers,theseproductsgeneratecaloricenergyorbiogas.InthepaperofDemirbasandDemirbas[3],theauthorssaythatthedecreasingreservesoffossilfuelsandtheirpotentialrisktotheenvironment,suchastheemissionofgreenhousegasesintotheatmosphere,hasledtothedevelopmentofrenewableenergysources,sustainabledevelopmentandeco-friendlyconcepts.Nevertheless,althoughrenewableenergyhasbeentheobjectofspecialattentioninmanycountries,onaglobalscalelessthan15%ofthemainsupplyofenergycomesfromthismodality[5].AccordingtoBrazilsMinistryofMinesandEnergy(MME)[6],theenergymatrixof43.8%ofthecountrysenergysourcesisrenewable,dueinlargeparttotheintensiveuseofwoodandhydroelectricenergy.However,solarandwindenergystillrepresentonlyaminorfractionofthetotalenergysupplyinmostcountries,includingBrazil.Themajorchallengeliesinintegratingahighfractionofintermittentresourcesasalargepartoftherenewableenergyintheelectricpowersupply,andinincludingthetransportsectorinthesestrategies[5].

3.1.Generationofbiogasbybiomass

Methane(CH4)isoneoftheGHGswithaglobalwarmingpotential23-foldgreaterthanthatofcarbondioxide(CO2),andahighenergypower.Methaneemissionsintotheatmosphereoriginatefrommanysources,suchasanaerobicbiodegrada-tion,ruminantdigestion,biomassburning,etc[7].Thesesourcesarenaturalandanthropogenic,theformerrepre-senting40%andthelatter60%ofthetotalmethaneemissions.Bothnaturalandanthropogenicsourcesmayinvolvedegradationprocessesbymicroorganisms,whichcanbedividedintoaerobic,facultativeandanaerobicdegradation[8].Theconditionsofthemediuminwhichdegradationoccurs,withthepresenceorabsenceofoxygen,willdenetheconsortiumofmicroorganismsthatactinthedecompositionoftheorganicmatter.Inanaerobicdegradation,oxygenistoxictomicroorganisms,andcarbondioxideandmethane,whicharepresentinbiogas,areeliminatedasdegradationby-

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products.Theproductionofmethaneinanaerobicsystemsisduetomethanogenicmicroorganisms.Theaveragecompositionofbiogasproducedbyanaerobicdegradationvariesfrom50to80%ofmethaneand20e50%ofcarbondioxide,besidestracesofothergases[9].Biodigestersareoptimizedanaerobicdegradationsystemsthatuseabout50%oforganicwastesto50%ofdilutionliquid,whichmaybewater(especiallyrainwater),sewage,oranyotherliquidefuentthatisnotharmfultothesystem[10].Iftheorganicwastesarenotsufcientlydissolvedinwater,thepercentageofliquidshouldbeincreasedinordertoreachamoisturecontentofabout90%.Itisimportanttopointoutthatanaerobicdegradation,andthereforethebiodigester,requireshightemperaturestoachieveitsmaximumefciency,asdemonstratedinastudybyCastroandCortez[12],whofoundthat31Cistheoptimaltemperatureforthedegradationofcattlemanure.Oneofthepossiblesolu-tionstomaintainthesehightemperaturesisproposedbyAxaopoulusandPanagakis[9],whosuggesttheuseofsolarheatinginbiodigesterstreatingpigmanureinGreece,wheresolarcollectorswereinstalledonthecanvascover,providinganaveragetemperatureof35Cinsidethebiodigester.Someoftheadvantagesoftheuseofbiodigesters,inadditiontothepossibleuseofbiogas,aretheuseofwastesthatwouldotherwisebepollutiveifdischargeddirectlyintotheenvironment,duetotheirhighloadoforganicmatter,andthereductionofodorsresultingfromthispractice[13];theremovalofpathogensthatreinfesttheanimalsthatfeedonpasturesfertilizedwithuntreatedwastes;theproductionofbiosolidsthatcanbeusedasorganicfertilizersinagriculture;theproductionofbiofertilizersorbioliquids,alsorichinnutrients,forfarming,aquacultureorasleaffertilizers[11].Domesticsewagecanbetreatedbyanaerobicprocessessuchasupowanaerobicsludgeblanket(UASB)reactors,whichremove60e80%ofthebiochemicaloxygendemand(BOD)andgenerate65e80%ofmethane[14].AccordingtoLiedl,BombardiereandChateld[15],degradation-generatedbiosolidsorbioliquidscanbeusedjointlywithmineralfertilizersinavarietyofvegetablecultures,providingayieldcomparabletothatobtainedwiththeexclusiveuseofmineralfertilizer,andreducingthecostoftheproductionprocess.Biogasgeneratedbyanaerobicdegradationcontainsabout65%ofmethaneand35%ofcarbondioxide[16].Onecubicmeterofbiogasisequivalentto3.47kgofwood,0.63Lofkerosene,0.61Lofdieseloil,1.5kgofcoal,1.25kW/hofelectricity,0.45kgofliqueedpetroleumgas,and0.5kgofbutane,andcanbegeneratedfromthedegradationof13kgofmanure[17].Methanecanbeusedasanenergysourceinvarioustypesofequipment,suchasstoves,engines,generators,lightingingeneral,heatersforhomesandanimals,refrigerators,green-houses,graindryers,incubators,etc[18].Althoughanaerobicdegradationmayproduceunpleasantodors,methaneisodorless.Biogasthatemitsunpleasantodorsprobablycontainsothergasessuchashydrosulfuricgas.Themethanegeneratedintheabovedescribedbiomassdegradationprocessescanbechanneledtosmallplantswhereitwillbeusedtorunengine-drivenpowergenerators.Methaneproductionisadvantageousifitinvolvestheopti-mizationofprocesses,reachinghighefciencyasafunctionofinvestmentsininstallations[19].

Ineconomicterms,biogascanprovidesignicantenergybenetswhenitsproductioniscontrolledandinvestmentscangeneratenancialreturns,includingthecostsofnesandalignmentwithenvironmentallegislation[11].Thesolidwastesofagriculturerepresentapotentialenergysourceifconvertedintomethane[16].Inruralareasorvillagesnotconnectedtotheenergygrid,orwhichseektoreducetheirelectricpowerexpenses,theavailabilityofbiogasrepresentsnotonlyanimprovementinthequalityoflifeoftheirresidentsbutalsoabusinessopportunity[3].Itshouldbekeptinmindthat,inadditiontotheaforementionedbenets,thereisthepossibilityofsellingcarboncredit.Brazilalreadyhasseveralprojectsthatincludecleandevelopmentmechanisms(CDM)forthesaleofcarboncredits.AccordingtotheMinistryofMinesandEnergy[20],45ofthe207carbonsequestrationprojectsregisteredattheUnitedNationsuptoApril2006wereBrazilianprojects.ThereductionofmethaneemissionsispresentinthreeprojectsthatarealreadyissuingRenewableEnergyCerticates(RECs):thesanitarylandllsofNovaGerar(RJ)andBandeirantes(SP)andtheSadiabiodigesterprojectinwhich3.5thousandsmallfarmersparticipate,mainlypigfarmersinthestatesofSantaCatarinaandParana.Thesearchforenergyselfsufciencyisastrongincentiveforthedevelopmentofprojectsthattakethebestpossibleadvantageoftheenergypotentialofaproductiveplant,beitrural,industrialorurban.AnexampleofthissearchispresentedbyAngoneseetal.[21],whoevaluatedtheenergyefciencyofaswineproduc-tionsystemwithtreatmentofwastesinabiodigesterinthemunicipalityofOuroVerdedoOeste(PR).Theauthorsdemonstratedthepossibilityofmaximizingtheenergypotentialofpigfarmwaste,withintheproductionstructureitself,reducingtheenvironmentalimpactscausedbythedisposaloftheseuntreatedwastesintheenvironment.Accordingtotheirstudy,theproductionofwasteshasaconsiderableenergyvalueofabout30%ofthesystemstotalenergyoutput,sinceitsusecanminimizetheimportationofenergyfortheentiresystem.

3.2.Biodiesel

Biodieselisaneconomicallycompetitiveandenvironmentallyfriendlyalternativefuelobtainedfromrenewablesources[22].InBrazil,theNationalPetroleumAgencys(ANP)Adminis-trativeRuleno.255/2003establishedapreliminaryspecica-tionfortheuseofbiodieselinmixturesofupto20%(B20),whichissimilartotheEuropeanandAmericanspecications,butwithsomemeasureofexibilitytomeetthecharacteris-ticsofthenationalrawmaterials.Asfortheeconomicaspects,Demirbas[16]comparesthecostsofprojectsinvolvingbiodiesel(originatingfrombothvegetableoilsandanimalfat)againstdieselprices,presentingnumbersthatdemonstratethatthelatterisstillacheaperenergysource,atleastintheUnitedStatesandinsomeEuropeancountries(i.e.,whilethecostofbiodieseloscillatesfromUS$0.30to0.69,thepriceofdieselvariesfromUS$0.20to0.24).Theuseofbiodieselisjustiedbypositiveexternalities,someofthemainonesbeingtheinterestandengagementof

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asignicantportionoflocalpopulationsinthecauseofenvironmentalconservation.Biodieselproductioncostsdependessentiallyonthecostoftherawmaterial,thevegetableoiloranyotherfattysubstance,andthecostsofindustrialprocessing.Thus,thecostofvegetableoilgenerallyrepresentsabout88%ofthecostofbiodieselwhenitisproducedinhighcapacityplants,whichisthereasonfortheinterestinreducingthecostsofrawmaterials,sothateventuallythefattymaterialcanbeobtainedfromindustrialwastes,suchasusedfryingoilandanimalgrease[23].ThepotentialmarketforbiodieselinBrazilisdeterminedbythemarketofpetroleum-derivedproductsandbytheobligatorymixtureofupto5%ofbiodieselindiesel,asestablishedbyLaw11097of13January2005.Thepurposeofthislaw,whichregulatestheintroductionofbiodieselintheBrazilianenergymatrix,istoincreasetheparticipationofbiofuelsinthenationalenergymatrix,basedoneconomic,socialandenvironmentalconsiderations[24].ThetotaldemandfordieseloilinBrazilin2007wasintheorderof41.5millioncubicmeters,whiletheproductionofbiodieselthatyearwas402thousandcubicmeters[25].Theuseofbiofuelsingeneralreducesthemainlocalemissionsassociatedwithdiesel,notablythatofparticulatematerial,aswellascarbonmonoxideandhydrocarbons,SOxesulfuroxide,exceptNOxenitrogenoxides(2e4%,withB20)[26].Moreover,biofuelsarenontoxicandbiodegradableformsofenergywhosewidespreadusewouldcontributeconsiderablytoreducepollutioninlargeurbancentersandpopulationconglomeratesaroundtheworld.

3.3.Alternativeusesofwastesonruralproperties

Withthereductionoftheprotmarginineveryproductivesector,theaimshouldbetoseektheminimumlossofanyinputandthemaximumefciencyofeveryprocess.Inthissense,ruralpropertiesshouldseetheirwastesasrawmate-rials,encouragingresearchandthequestforsustainablealternativesfortheirprocesses[10].Adescriptionisgivenbelowofseveralresearchesandcasesofexploitationofby-productsfromcoffeecultivationandtheproductionofbio-diesel,expandingthelistofwastesmentionedearlierherein.RathinaveluandGraziosi[27]presentseveralalternativesfortheuseofcoffeeprocessingby-products.Instudiesofpigfeed,theauthorsclaimthatcornmaybereplacedbydehy-dratedcoffeepulpinupto16%ofthetotalfeed,withnoharmfuleffectsintermsofweightincreaseorfoodconver-sion.Anotheruseforcoffeepulptheymentionistheproductionoforganicfertilizerbycomposting,withareten-tiontimeofthreeweeks.Coffeehuskscanalsobeusedtogenerateenergybyburning.Anotherstudyontheuseofcoffeeby-productswaspre-sentedbyRibeiroFilhoetal.[28],whostudiedtheirsubstitutionofgroundcornwithhusksandcobs(GCHC)inFresian-Zebucrossbredbullocksinthepost-weaningphase.Theauthorsconcludedthatitisfeasibletosubstituteupto30%ofGCHCwithcoffeehusksinthefeedconcentrate.Intheproductionofbiodiesel,themainresidueisglycerin,whichisoftenusedasarawmaterialintheproductionofsoaps.However,theliteraturelistsotherpossibleusesof

glycerin,asacomponentofanimalfeedandasaco-substrateinbiodigesters[29].TheuseofglycerininpigfeedisdiscussedintheworkofHoltkamp,RottoandGarcia[30].Theseauthorsstatethatrawglycerinfrombiodieselproductioncontainsapproximately85%ofglycerol,10%ofwaterand3e7%ofsalts,withagrossenergyof3600e3750kcal/kg,dependingonitspurity(pureglycerolcontains4305kcal/kgofgrossenergy).Theauthorsstudiesonpigsinthefatteningphaseindicatethatglycerolishighlypalatableanddigestibleandthat10%canbeaddedtopigfeed,improvingitandmaintainingthepigsgrowthperformance.Anotheruseforglycerinfrombiodieselproductionisinbio-digesters[31].Thisresearcherreportsthattheadditionof6%ofglycerininabiodigesterdegradingswinemanurecanincreasetheproductionofmethaneinthesystembyabout180%.

4.Method

Thepresentresearchwasbasedonthecasestudymethod,whichYin[32]denesasempiricalquestioningthatinvesti-gatesacontemporaryphenomenonwithitsreallifecontexts,whentheboundariesbetweenthephenomenonandthecontextarenotclearlyevident,andinwhichmultiplesourcesofevidenceareused.ItwasdecidedtostudyasinglecasebecausethisphenomenonisarecentoneinBrazil.ThisresearchwasconductedonaruralpropertyinthemunicipalityofCaconde(SP),situated290kmfromSaoPaulo,ontheborderwithMinasGerais.Thepropertycovers250haandinvolvesdifferentactivities:pigproductionandporkprocessing,coffeeplanta-tions,andcornplantationsfortheproductionofpigfeed.Throughthisresearch,wesoughttoascertainhowandwhythechangesontheanalyzedpropertywereimple-mented,andtomakeasubsequentevaluationoftheadvan-tagesgainedfromtheinvestment.Yin[32]suggeststhatsixsourcesofevidenceshouldbeused,asfaraspossible,toobtainagoodcasestudy,namely:(1)documentation,(2)lerecords,(3)interviews,(4)directobservations,(5)participantobservations,and(6)physicalartifacts.Indocumentationusedinthisresearchconsistedofcerticatespresentedbyoneoftheowners,Mr.JoaoPauloMuniz,aswellasanalysesofthequalityofthebiodiesel,thepatentsforbiodieselproductionfrompigandcowfat,andnewspaperandjournalarticlesabouttheenterprise.Theprincipaldataforthestudywerecollectedfromsemi-structuredinterviewswithMr.Muniz,whichwereheldatthestudysite.Thedirectobservationsofthedifferentactivitiesonthepropertyenabledustofollow-uponthedatapresentedbytheinterviewee,andprovidedamoredetailedandsafeviewoftheresearchobjects.Asforthephysicalartifacts,thevisitcoveredtheactivitiesandproductsdevelopedorusedonthefarm,providingdirectcontactwithpracticallyallofthem,thusfacilitatingourunderstandingofthepigbreedingprocess,porkprocessing,andtheproductionofpigfeed,biogas,biofertilizer,electricpower,biodiesel,soap,toiletsoap,detergentandcompostedfertilizer.

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Thetheoreticalfoundationforthecasestudywasaresearchofnationalandinternationalbibliographicsources.Theenvi-ronmentalandsocialvariableswereanalyzedqualitatively,andseveralquantitativeanalyseswereusedtoevaluatetheeconomicvariables.

5.Casestudy:Pork-Terra

Thecasestudywascarriedoutonaruralpropertyof250halocatedinthemunicipalityofCaconde(SP),whosemainactivitiesarepigbreeding,porkprocessing,coffeeplantationsandcorngrownforanimalfeed.Thefamilybusiness,calledPork-Terra,isownedbythreepartners,afather,son(JoaoPauloMuniz)anduncle.Thepigbreedingactivityonthepropertydatesbackto1980,buttheprocessingofprimeporkcutsandthefabricationofporkcracklingstartedabout20yearsago.Severalhygiene,environmentalandeconomicaspectsledthepartnerstoreviewthefarmsproductiveprocess.Theexpansionofpigproductionledtoasignicantincreaseinthevolumeofmanure,causingproblemswithneighborsandwiththeenvironment,withunpleasantodors,iesandthelaunchingofwastesintoastream.Feedingtheanimalsrequiredplantingcorn,whichbeganin1980,requiringfertilizers,asdidthecoffeeplantations,anolderactivitydatingbackto1920.Theareasoccupiedtodaybyplantationsconsistof90haofcornand75haofcoffee.Itshouldbenotedthat100%ofthecorngrownonthefarmisdestinedfortheproductionoffeedforthefarmspigs.Thevariousformsofenergy(electric,dieselandgas)neededformeatprocessing,aswellasforthefarmsotheractivities,theemployeeshomesandthefarmsvehicles,wasalsosubstantial.Inadditiontoenergy,largequantitiesofsoaparealsousedtomaintainproperhygieneconditionsinthefacilities.Withthehelpofqualiedprofessionals,evaluationsweremadeofthepossibilitiesforeliminatingproblemsand,particularly,theuseofwastestogenerateenergy,fertilizers,animalfeed,andotherproductsrequiredforthefarmsprocesses.Approximatelytwoyearsago,thebiodigesterswereinstalledandstudiesonbiodieselproductionfrompigfatwereinitiated.Today,Munizholdsapatentfortheproductionofbiodieselfrompigfatandisawaitingnewsaboutapatentheledforbiodieselproductionfromcowfat,whichheexpectswilltakeanothervemonths.TheinitialinvestmentinthemodicationsonthefarmwasaboutR$100,000.00,includingthebiodigestersandtheminibiodieselprocessingplant.However,thebusinessmanclaimsthatthesavingsresultingfromtheenterprisemorethancompensatesfortheinvestment,besidestheenviron-mentalandsocialbenetsithasyielded.

5.1.Pigbreedingandporkprocessing

Thepigbreedingenterprisecomprises200breedersows(Fig.1eright),fromwhichoriginatethe80pigsslaughteredperweekfortheporkprocessingenterprise.100%ofthe

processedporkcutscomefromthefarmitself,withporkcracklingrepresentingthemosttraditionalproductofthemix.Tomaintainthehygieneinallthepigbreedingfacilities,constantwashingisdone,whichrendersthemanuresuf-cientlymoisttobesenttothefarmsbiodigesters.Afterthepigletsareweanedattheageof21days,theyaretakentoacompartmentwherebiogasisusedforheatingtoabout35C(Fig.1eleft).Twobiodigestersreceivethewastesfromtheseactivities.Thepigfatteningandslaughteringfacilitiessupplythewastesforathirdbiodigester,includingthebloodleftafterslaughtering.Porkprocessingiscarriedoutusing100%ofgasproducedinthebiodigesters,whichdrivestheboilerthatheatsthewaterusedforskinningtheanimals.Theproductmixconsistsofprimecuts,sausages,smokedporkandporkcrackling.Theproductsarevacuum-packed,manyofthemrequiringonlycoolingandnotfreezing.Thefatisrenderedandsenttothebiodieselproductionplant.

5.2.Processingofswinewastes:biogasandbiofertilizer

Threebiodigesterscalledminibiodigesters,whoseconstructionissimpleandfast,wereinstalledtoprocessthewastesfrompigproductionandporkprocessing.Theconstructionofabiodigesterconsistsofdiggingatrenchwithanearthdiggingmachine,liningthebottomandsidesofthetrenchwithaplasticcanvastopreventpercolationoftheliquidintotheground,andcoveringthistankwithanothercanvas,whichinatesasbiogasisproduced(Fig.2eleft).Munizstatesthatinthecoldestseason,biogasproductiondecreases,recoveringpromptlyinthewarmermonths.Itshouldbepointedoutthatthereisnounpleasantodorinthesurroundingsofthebiodigester-biofertilizertankset.After30e40daysofdegradation,theresiduefromthebiodigesteristransferredtoanopentrench,alsolinedwithcanvas,nexttothebiodigesters,wherethebiofertilizeriscollected(Fig.2eright).Theanalysisofthebiofertilizerproducedonthefarmindicatedconcentrationsof0.5e4.0%ofnitrogen,0.5e5.0%ofphosphorus,and0.5e3.0%ofpotassium,andabout90e95%ofwater.Thebiofertilizerisusedinthecoffeeandcornplantations,althoughitcontributeswithonly40%ofthetotalfertilizerrequired,andiscomplementedwithindustrialfertilizer,sincetheexclusiveuseofbiofertilizerhasprovedinsufcienttosupplythenutrientsneededtomaintainproductionatthelevelobtainedusingonlyindustrialfertilizer.Allthebiogasproducedinthebiodigestersisusedonthepropertyitselftogenerate50%ofitselectricpowerneeds,includingthe17homesofemployeesand50%oftheofthecoldstoragewarehouse,aswellasthevariousstovesforporkprocessingandfatrendering,preparationofemployeesmeals,productionofbiodieselandpuricationofglycerin,aswellasforheatingthepigletnursery,andforcoffeedrying.Toreducethecorrosionpowerofthebiogas,Munizexplainsthatapurierintheformofacoilwasbuiltafewmetersunderground,throughwhichthebiogaspasses,startingatabout35C,thetemperatureatwhichitexitsthe

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